Bimetallic signal device for appliances

ABSTRACT

A control means for providing a signal indicating a shutdown of an appliance, the control means including a bimetallic element connected in series with the power line to the appliance, the bimetallic element being arranged to deflect substantially upon passage of the current from the source and to return to its original condition upon cessation of the current, the bimetallic element being engageable with a stationary contact for actuating a signal generating device.

United States Patent [1 1 Wiechert I Jan. 16,1973,

[ BIMETALLIC SIGNAL DEVICE FOR [56] References Cited APPLIANCES UNITEDSTATES PATENTS [751 Invent Jay wiechel", Benton Harbor, 2,027,118 1/1936Presser ..337/l6 Mi I 3,125,422 3/1964 Thunander ..2l9/364 x 73 A 1Wll'l lC t' ,B t H 1 sslgnee zg orpora [on en on at PrimaryExaminer--Robert K. Schaefer Assistant ExaminerWilliam J. Smith {22]Filed: Feb. 2, 1972 Appl. No.: 223,000

Related U.S. Application Data Continuation of Ser. No. 48,l50, June 22,I970.

Att0rneyHill, Sherman, Meroni, Gross & Simpson [57] ABSTRACT A controlmeans for providing a signal indicating a shutdown of an appliance, thecontrol means including a bimetallic element connected in series withthe power line to the appliance, the bimetallic element being arrangedto deflect substantially upon passage of the current from the source andto return to its original condition upon cessation of the current, thebimetallic element being engageable with a stationary contact foractuating a signal generating device.

4 Claims, 6 Drawing Figures BIMETALLIC SIGNAL DEVICE FOR APPLIANCES'This is a continuation of application Ser. No. 48,150 filed June22,1970.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention isin the field of signal generating devices which provide an audible orvisual signal to inform an operator that an appliance has completed itscycle and is de-energized.

2. Description of the Prior Art Many appliances have circuitry whichprovides end-of-cycle signals. For example, many dryers operate toactuate a buzzer which is connected to a centrifugal switch on the drivemotor. A timer contact normally keeps the buzzer de-energized. At theend of the dryer cycle, however, when the timer-operated switch opens,the buzzer is energized until the centrifugal switch has transferred toits at rest position.

In U.S. Pat. No. 3,132,003, there is disclosed a dryer control circuitincluding an end-of-cycle signal solenoid. This solenoid is shunted by abimetal switch which is part of the temperature-sensing thermostat.

This thermostat operates at a pre-determined temperature and uponopening, the thermostat tie-energizes the motor and briefly energizesthe end-of-cycle signal.

U.S. Pat. No. 3,334,340 describes an end-of-cycle signal which can belocated at a remote location from the appliance. The signalling deviceincludes a transmitter which is associated with the appliance, and theremote receiver, which can be plugged into the same alternating currentdistribution system as the appliance. At the end of the cycle, or atother appropriate times, the transmitter is briefly energized, causing asignal to be sent out over the power distribution system for the home.The receiver is plugged into this system so is triggered into activityby the signal sent out by the transmitter. The receiver can then actuateeither a visual or audiable means to indicate to the operator that aparticular condition exists in the appliance.

SUMMARY OF THE INVENTION The present invention provides a signal devicewhich is arranged to be connected between the line cord energizing theappliance and the wall receptacle so that the signal device can be usedwith any continuously running appliance to indicate that the appliancehas finished the particular cycle or has stopped. The control unit ofthe present invention is self-contained, and does not take up space inthe appliance control console or complicate the control, circuit. Theactuator mechanism of the improved control system is a simple low-costelement which can function with various types of end-of-cycle signals,including remotely operated signalling devices.

The control device of the present invention includes a bimetallicelement which cooperates with a stationary contact. The bimetallicelement is heated by means of current directly from the power input tothe appliance. The characteristic of the bimetallic element is such thatupon initial energization, the bimetallic element is warped at arelatively rapid rate and makes only momentary contact with thestationary contact at this time. When, however, the line current isterminated, the bimetallic element moves back to its original positionat a much slower rate, so that it engages a stationatime the signal isgenerated by suitable signalling means.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a somewhat schematic view ofa dryer installation employing the improvements of the presentinvention;

FIG. 2 is a circuit diagram of a transmitter circuit employing abimetallic element for energizing same;

FIG. 3 is a wiring diagram of a receiver which can be used inconjunction with the transmitter shown in FIG. 2 to generate a visualsignal;

FIG. 4 is a view in perspective, partly broken away, of a control unit;

FIG. 5 is a fragmentary view in elevation showing the position of thebimetallic element in its unenergized and fully energized positions; and

FIG. 6 is a schematic view of another circuit which can be employed inaccordance with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, reference numeral 10has been applied generally to a dryer for purposes of illustration, butit will be recognized that the control circuits of the present inventioncan be used in any type of appliance. The dryer 10 is shown providedwith a programmer 11 and having a line cord 12 receiving energizationfrom a wall receptacle 15. The plugs of the line cord 12 are energizedfrom the alternating current distribution system 16 through a signalcontrol means 30. Other wall receptacles such as that shown at 15' inFIG. 1 are connected to the distribution system 16, and a receiver 50 isplugged into the receptacle to give an audible or visual signal everytime the transmitter located in the control unit 30 is energized.

The mechanical structure of the control device 30 is best seen in FIG. 4of the drawings. This unit is selfcontained and includes a pair of maleconnectors 21 and 22 arranged to be received within a standard wallreceptacle. On the opposite side of the housing, there is a sockethaving terminal receiving portions 23 and 24 into which the line cord ofthe appliance is connected for operation. Located within the controldevice 30 is a circuit board 26 on which there is mounted a bimetallicactuator 20. As best seen in FIG. 5, the bimetallic actuator 20 isarranged to cooperate with a stationary contact 25, the latter beingpositioned between the at rest position shown in full line in FIG. 5 andthe warped position shown in dotted lines 20 in FIG. 5. Thus, as thebimetallic element 20 is rapidly heated up by the line current goingthrough it, a contact 27 on the bimetallic element makes momentarycontact with the stationary element 25. The bimetallic element 20 hasthe characteristic of fast heating and slow cooling. Accordingly, whenthe appliance such as the dryer 10 is first energized, it quickly movesto the position shown at 25 in FIG. 5. When the appliance isdeenergized, the bimetallic element 20 slowly returns to its at restposition, so that the contacts 25 and 27 are engaged for substantiallylonger periods of time.

In FIG. 2 there is illustrated a transmitter circuit with which thebimetallic element 20 can be combined. It

will be seen that the element is in electrical series with the powerinput to the appliance. The terminals 21 and 23 are connected to eachother and to one side of the distribution line 40. The other line 45 isconnected to the stationary contact 25. Accordingly, when the bimetallicelement 20 is transferring from the dotted line to the solid lineposition, contacts 25 and 27 become engaged for a short predeterminedperiod of time to energize the transmitter circuit. 35 When contacts 27and 25 are engaged, alternating current is impressed across a half waverectifier diode 31 which is connected in series with a limiting resistor32. A

capacitor 33 is placed across the line to serve as a filter capacitor,and a pair of resistors 34 and 35 is placed in series across the line toserve as a voltage dividing network. An oscillator circuit 36 provides atuned circuit tuned to a predetermined resonant frequency. This circuitincludes coils 37, 38 and 39 in combination with a capacitor 41.

A transistor 42 is provided with a bias resistor 43 across which thereis a signal by-pass capacitor 44. Another by-pass capacitor 46 appearsacross the resistor 35 while a 60-cycle blocking capacitor 47 isconnected between one side of the. inductance coil 37 on the other sideof the line.

The transmitter circuit of FIG. 2 is more or less conventional and isillustrated in the drawings merely for sake of completeness. The circuitis designed to provide a signal at a predetermined frequency whichhappens tobe convenient for a particular installation.

A receiver suitable for use with the transmitter of FIG. 2 is shown inFIG. 3. The receiver 50 is energized from an alternatingcurrentdistribution system 16 by means ofconductors 51 and 52. The inputvoltage appears across the combination of a 60-cycle blocking capacitor53 and the primary 54 of an input coil generally indicated at 56. Acrossthe secondary 58 of the input coil 56 there is a capacitor 57 forming atuned circuit therewith. The secondary 58 is tapped off and the signalcurrent passes through a diode 59 to the base of a transistor 61. Asignal filter capacitor 62 and a base biasing resistor 63 are connectedbetween the base and the emitter of the transistor 61.

The input line voltage is transformed into a series of half wave pulsesby means of a half wave rectifier diode 64. The half wave pulses aresmoothed out by means of a voltage divider network consisting ofresistors 66 and 67and'a' filter capacitor 68. This rectified voltage isused to energize a neon tube 69 which has one of its electrodesconnected to the collector of the transistor 61. A collector biasingresistor 71 is connected across the neon tube 69. Accordingly, when thetransmitter sends outza signal at a pre-determined frequency, thereceiver 50 which is tuned to this frequency will be energizedand'enough voltage will be generated across the neon tube 69 to providea visible signal for as long as the transmitter is operating.

An alternate form of the invention is shown in FIG. 6 which is arrangedto position a signal source immediately at the appliance rather thanremote from the appliance. The signal device 28 can be provided with aself-contained unit such as that shown in FIG. 4. The

ing an audible signal indicating that the appliance with which thesignal device is connected has ceased operation.

The signalling devices of FIG. 4 or FIG. 6 are connected between theline cord of the appliance and the wall receptacle. When a transmittersuch as that shown in FIG. 2 is used, a receiver 50 of the type shown inFIG. 3 is plugged into some other receptacle in the alternating currentdistribution system. When the operator initiates operation of theappliance, the bimetallic element rapidly shifts to its energizedposition 20, energizing the signal mechanism. When the appliance hasfinished the cycle at which it has been set and ceases operation, thebimetallic element 20 slowly cools to return to its original position.During this cooling, movable contact 27 makes contact with stationaryactuator of the signal device is a bimetallic element 20 6 having amovable contact 27 adapted to contact a stationary contact 25 whenmoving between the full line contact 25, energizing the transmitter ofFIG. 2 for the buzzer 29 of FIG. 6. Energization of the transmitter 30causes a signal to be impressed on the alternating current distributionsystem, to actuate receiver 50 and provide a visual indication by meansof neon tube 69. With the device of FIG. 6, the buzzer 29 is brieflyenergized to create an audible signal that the appliance has finishedits cycle. As the bimetallic element 20 continues to cool, contacts 25and 27 re-open, thereby deenergizing the signal mechanism.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows: I

I. An appliance energizing system comprising:

means for connecting said appliance to a source of electrical power,

a control means connected between said appliance and said source ofelectrical power, said control means including 7 an elongated warp typebimetallic element connected in series with said source of electricalpower and arranged to deflect substantially and rapidly upon passage ofthe current from said source therethrough, and to return to its originalcondition substantially more slowly upon cessation of said current, 1said element having a first contact thereon at the free .end thereofmovable through a path of movement of substantial length,

a stationary second contact disposed in the path of movement of .saidfirst contact and having an effective width less than the length of thepath of movement of said first contact so that it is only momentarilyengageable with said first contact during the period of such rapiddeflection of said bimetallic element and being engageable in wipingengagement with said first contact for a prolonged period upon cessationof said current, and

signal means actuated upon engagement of said first contact with saidstationary second contact.

2. The system of claim 1 in which said signal means includes atransmitter arranged to feed a signal into said source of electricalpower and a receiver responsive to signals generated by saidtransmitter.

3. The system of claim 2 in which said receiver is separate from saidtransmitter and includes a visual indicator means actuated only uponreception of a signal from said transmitter.

4. The system of claim 1 in which said appliance is a 5 dryer.

1. An appliance energizing system comprising: means for connecting saidappliance to a source of electrical power, a control means connectedbetween said appliance and said source of electrical power, said controlmeans including an elongated warp-type bimetallic element connected inseries with said source of electrical power and arranged to deflectsubstantially and rapidly upon passage of the current from said sourcetherethrough, and to return to its original condition substantially moreslowly upon cessation of said current, said element having a firstcontact thereon at the free end thereof movable through a path ofmovement of substantial length, a stationary second contact disposed inthe path of movement of said first contact and having an effective widthless than the length of the path of movement of said first contact sothat it is only momentarily engageable with said first contact duringthe period of such rapid deflection of said bimetallic element and beingengageable in wiping engagement with said first contact for a prolongedperiod upon cessation of said current, and signal means actuated uponengagement of said first contact with said stationary second contact. 2.The system of claim 1 in which said signal means includes a transmitterarranged to feed a signal into said source of electrical power and areceiver responsive to signals generated by said transmitter.
 3. Thesystem of claim 2 in which said receiver is separate from saidtransmitter and includes a visual indicator means actuated only uponreception of a signal from said transmitter.
 4. The system of claim 1 inwhich said appliance is a dryer.